Concrete joint form



8, 1967 R. N. ATKINSON 3,334,558

CONCRETE JOINT FORM Filed May 24, 1965 I N\ "ENTOR.

RAY N. ATKINSON BY ATTORNEYS United States Patent 3,334,558 CONCRETE JOINT FORM Ray N. Atkinson, Hillsborough, Calif, assignor to Guy F.

Atkinson Company, San Francisco, Calif., a corporation of Nevada Filed May 24, 1965, Ser. No. 458,117 4 Claims. (CI. 9418) The present invention relates generally to concrete pavement and more particularly to a concrete joint form for use therein.

In the construction of canal linings, roadways, airport runways and other paved surfaces, it is common to provide weakened planes whereby any fracture or cleavage will take place along controlled planes. Such weakened planes have, for example, been formed by providing an open groove in the concrete paving, by embedding strips of material in the concrete paving, or by cutting the concrete after it has hardened.

In certain instances as, for example, in canal linings, it may be desirable to form a groove which is sealed with a rubber rod and mastic cement just prior to filling the canal with water. When such a lining is allowed to stand exposed for any period of time, the elements will cause dust, dirt, sand and the like to collect in the groove and to fill the same. Furthermore, as the lining contracts and expands, it will, of course, fracture along these weakened planes, and weeds and the like may grow through the pavement from the earth underneath. Thus, prior to performing the sealing operation, it becomes necessary to clean the groove as, for example, by sandblasting, scraping or the like.

It has been suggested that a removable form or filler should be inserted in the groove during or just after a paving operation to cover or protect the groove. Such a form could also include means for sealing the groove whereby the groove remains sealed during thetime the lining is exposed to the elements. In certain instances, it may be desirable merely to provide a concrete joint form and leave the same in place as a permanent filler or sealer.

It is a general object of the present invention to provide an improved concrete joint form for use in paved concrete surfaces.

It is another object of the present invention to provide a concrete joint form which is light, strong and economical.

It is still a further object of the present invention to provide a concrete joint form which is capable of temporarily or permanently sealing a groove formed in concrete pavement.

The foregoing and other objects of the invention will become more clearly apparent from the following description taken in conjunction with the accompanying drawing.

Referring to the drawing:

FIGURE 1 is a perspective view showing a concrete pavement incorporating a concrete joint form in accordance with the invention;

FIGURE 2 is an elongated view of the concrete joint form of FIGURE 1;

FIGURE 3 shows the concrete joint form with theconcrete developing a cleavage plane;

FIGURE 4 shows the concrete joint form installed with the concrete at the joint separated; and

FIGURE 5 shows a joint having the form removed and sealed with a seal and mastic.

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Referring to the drawing, FIGURE 1 shows a concrete pavement 11 having a concrete joint form 12 installed therein. Referring more particularly to FIGURES 1 and 2, the concrete joint form includes a top wall 13 formed of first and second substantially coplanar portions 16 and 17. The concrete joint form includes downwardly depending side walls 18 and 19 which may be formed from .a single piece of material and which are substantially V-shaped. The distal ends are joined along a longitudinal edge 21. This forms a point along which there is stress concentration and provides for cracking or cleavage of the concrete substantially along this edge.

The upper wall portions 16 and 17 extend beyond the side 'walls 18 and 19 to form wings 26 and 27. The wings taper and have a rather sharp feathered edge for purposes to be presently described.

During expansion and contraction of the concrete, the aligned adjacent portions of the upper walls abut one an other. To provide a large abutment surface, the upper walls are upset downwardly to provide spaced opposed abutments 28 and 29. Again, to add strength to the spaced walls, there may be provided inwardly extending interior fins 31 and 32 on opposed portions of the spaced walls. One of the fins is shown upset, 33, to provide an abutment for the distal end of the fin 31. It is apparent that both fins might be upset, if desired, to provide a greater abutting surface.

Referring more specifically to FIGURES 3 and 4, it is seen that the feathered edges of the upper walls are slightly embedded in the concrete whereby the complete form is held in the groove formed in the pavement. As shown in FIGURE 3, the pavement is expanded and the abutting edges of the upper wall and the fins are in abutment and provide strength against further collapse of the concrete form. In FIGURE 4, the concrete is shown as contracting and separating. It is seen that the V-shaped outer walls open up and close to accommodate expansion and contraction of the pavement while maintaining a seal.

The concrete joint form may be formed by a single extrusion. The joint form may be made of a rather rigid thermoplastic material such as polyester.

Referring now to FIGURE 5, the form is shown removed from the concrete and a butyl rubber sealing member 36 inserted at the bottom of the V-shaped groove. The upper portion of the groove is filled with a mastic material 37, the seal 36 serving to retain the mastic material and to provide a weather-tight seal. It is, of course, apparent that in certain instances, the plastic concrete joint form may be permanently placed and serve the function of sealing the concrete.

Thus, it is seen that there is provided an improved concrete joint form. The form is inexpensive, durable and light.

I claim:

1. A concrete joint form for placement in a concrete slab to form a weaknened plane comprising a top wall including first and second adjacent aligned substantially coplanar portions, a pair of spaced side walls, one of said walls depending downwardly from each of said portions, said walls tapering towards one another and joined at their distal ends to form a continuous longitudinal edge spaced downwardly from said top wall, a pair of fins extending inwardly from each of said walls and arranged to have their digital ends abut one another to maintain the spacing of said wall.

2. A concrete joint form as in claim 1 wherein the ment.

3. A concrete joint form as in claim 2 wherein said upper walls extend beyond the side Walls to provide Wings.

4. A concrete form as in claim 1 wherein at least one edge of said inwardly extending fins is upset to form an abutment.

References Cited UNITED STATES PATENTS 2,230,688 2/1941 Irwin 9418 2,619,884 12/1952 Jacobson 94-18 3,136,022 6/1964 DOhI'Bn 9418 3,145,503 8/1964 Brechin 9418 JACOB L. NACKENOFF, Primary Examiner. 

1. A CONCRETE JOINT FORM FOR PLACEMENT IN A CONCRETE SLAB TO FORM A WEAKNENED PLANE COMPRISING A TOP WALL INCLUDING FIRST AND SECOND ADJACENT ALIGNED SUBSTANTIALLY COPLANAR PORTIONS, A PAIR OF SPACED SIDES WALLS, ONE OF SAID WALLS DEPENDING DOWNWARDLY FROM EACH OF SAID PORTIONS, SAID WALLS TAPERING TOWARDS ONE ANOTHER AND JOINED AT THEIR DISTAL ENDS TO FORM A CONTINUOUS LONGITUDINAL EDGE SPACED DOWNWARDLY FROM SAIT TOP WALL, A PAIR OF FINS EXTENDING INWARDLY FROM EACH OF SAID WALLS AND ARRANGED TO HAVE THEIR DIGITAL ENDS ABUT ONE ANOTHER TO MAINTAIN THE SPACING OF SAID WALL. 